My research interests focus on bridging the gap between systems biology and cell biology. My long-term goal is to couple my expertise in cell biology of the endoplasmic reticulum (ER) with high throughput tools and novel analytical methods to create a model for a self-contained unit within the cell. In the short term I plan to focus on the genes essential for maintaining homeostasis in the ER. The importance of a robustly functioning ER is underscored by its requirement for the normal development of multicellular organisms, especially differentiation of dedicated secretors such as plasma cells and insulin-secreting pancreas cells. To gain novel insights on maintenance of homeostasis in the ER, I propose to screen for all genes in whose absence the ER accumulates unfolded proteins. This can be measured accurately by utilizing a reporter for induction of the ER stress-induced unfolded protein response (UPR). Once all genes are identified, I plan to make a quantitative and accurate genetic interaction map, showing the extent by which a mutation in one of these genes changes the phenotype of all the others. Based on previous work, I believe that analysis of this map will allow me to predict functions for unknown proteins as well as organize all proteins into complexes and pathways. It will also allow me to study the hierarchy of the different processes involved in maintaining a fully functional ER. I propose to do this both in yeast (by using the yeast deletion strain library and a novel library of hypomorphic alleles of essential genes) and human cells (using RNAi technology). This comparison should allow me to define the evolutionary constraints leading to conservation of the organelle functions, thus developing a new understanding of the secretion process and its players in eukaryotes. [unreadable] [unreadable] Summary: All secreted and membrane-bound proteins essential for cellular communication and reaction to the environment are first translocated into the endoplasmic reticulum (ER) where they fold and mature into their native conformations aided by a variety of folding enzymes. A change in conditions in the ER causes activation of a stress response that mediates return to homeostasis. Mutations causing this response to be overactive or underactive have been reported to play a role in diseases as varied as cancer, cystic fibrosis (CF), diabetes, neurodegeneration and heart disease. Thus, gaining a deeper understanding of the genes regulating homeostasis in the ER and the stress response will allow us to treat such human pathologies. [unreadable] [unreadable] [unreadable]